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Management of cyanide poisoning begins with removal to fresh air Dermal decontamination is unnecessary if exposure has been only to vapor, but wet clothing should be removed and the underlying skin should be washed with soap and water Attention to the basics of intensive supportive care is critical and includes administration of 100% oxygen to all significantly symptomatic patients, mechanical ventilation as needed, circulatory support with crystalloid and vasopressors, correction of metabolic acidosis with IV sodium bicarbonate, and seizure control The cyanide-induced inhibition of cellular oxygen use might lead to the expectation that supplemental oxygen would not be of use in cyanide poisoning, but in fact, administration of 100% oxygen has been found to empirically exert a beneficial effect, possibly by affecting the interaction of cyanide with nitric oxide in mitochondria Symptomatic patients, especially those with severe manifestations, may further benefit from specific antidotal therapy Currently, two regimens are available in the United States The first, the original “cyanide antidote kit” utilizes a two-step process First, a methemoglobin-forming agent such as amyl nitrite or sodium nitrite is administered This causes dissociation of bound cyanide from the cytochrome oxidase and restores aerobic energy production Perhaps even more importantly, nitrites generate nitric oxide, which antagonizes the inhibition of cytochrome oxidase by cyanide The second step of the cyanide antidote kit is provision of a sulfur donor, sodium thiosulfate, which reacts irreversibly with cyanide to generate thiocyanate and sulfites, both of which are excreted in the urine Caution is warranted when using this cyanide antidote Nitrites result in vasodilation, which may enhance vital organ perfusion However, too rapid infusion may cause or exacerbate hypotension, and overproduction of methemoglobin may compromise oxygen-carrying capacity Thus, this therapy should be avoided in conscious patients with minimal symptoms and used with caution in patients, especially children, whose cyanide toxicity may be complicated by carbon monoxide poisoning (e.g., smoke-inhalation victims) However, a case study of adult smoke-inhalation victims treated with nitrites and sodium thiosulfate showed no complications of the nitrite therapy, and smoke inhalation should be regarded as a relative rather than an absolute contraindication to nitrite use The nitrite risk–benefit ratio becomes more favorable in the context of a severely intoxicated casualty of a terrorist cyanide vapor attack, and careful attention to proper dosing and rate of administration should allow safe use of this antidote Pediatric nitrite dosing depends on body weight and hemoglobin
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